An autonomous vehicle (AV) is a motorized vehicle that can operate without a human driver. An exemplary autonomous vehicle includes a plurality of sensor systems, such as but not limited to, a lidar sensor system, a camera sensor system, and a radar sensor system, amongst others. The autonomous vehicle operates based upon sensor signals output by the sensor systems.
Some vehicles include systems and components that are intended to mitigate various types of noise that result during operation of the vehicle. For instance, some vehicles include components that are intended to isolate the interior of the vehicle from the engine compartment in order to reduce audible engine noise in the interior of the vehicle. Some vehicles also include dampening components that are intended to dampen noise-causing vibrations of various parts of the vehicle. Passive approaches to noise mitigation in vehicles generally still allow significant noise in the interior of the vehicle, however, given the size, weight, and aesthetic constraints for noise mitigation components.
Active noise cancellation now finds application in headphones. Conventionally, active noise cancellation headphones incorporate a microphone, processing circuitry, and a speaker (ordinarily the same speaker used to output whatever the listener is listening to). The microphone is positioned in close proximity to the listener's ear and receives ambient noise from the listener's environment. The microphone outputs an audio signal indicative of the received noise. The processing circuitry receives the audio signal output by the microphone and generates a phase-shifted signal that is 180° out of phase with the audio signal. The phase-shifted signal is then output by the speaker, which is also positioned in close proximity to the listener's ear. This approach may be suitable to attenuate ambient noise when there is a microphone and a speaker positioned close to a listener's ear (e.g., within three inches of the listener's ear), but this approach exhibits poor performance when the microphone used to detect the noise and/or the speaker used to output the phase-shifted signal are farther away from the listener.